1. Field of the Invention
This invention relates to a lens barrel having at least a shutter speed priority automatic exposure system to be mounted on a camera body having at least a function of shutter speed priority automatic exposure system.
2. Description of the Prior Art
There has been a lens barrel of an aperture priority automatic exposure system which automatically controls a shutter speed in response to a preset aperture value, or a lens barrel of a shutter speed priority automatic exposure system which automatically controls an aperture value in response to a preset shutter speed, or both priorities automatic exposure system, which provides with both functions of aperture priority automatic exposure (AE) system and shutter speed priority AE system and which enables to selectively use the either system.
When a lens barrel of an aperture priority AE system is mounted on a camera body of a shutter speed priority AE system or of both priorities AE system which equipped with a shutter speed priority AE function and is operated for phototaking under shutter speed AE mode, it is not possible to make an appropriate phototaking. For enabling this operation, it is considered to provide at the side of camera body a signal member which is actuated when a lens barrel of aperture priority AE system is mounted so as to transmit a signal to a control system of camera body to the effect that such type of lens barrel is mounted. However, if a camera body is constituted in such a way as mentioned, and when a lens barrel of shutter speed priority AE system or of both priorities AE system is mounted on such camera body, there has been a problem to transmit a signal which shows that the mounted lens barrel is not of aperture priority AE system.